The highly developed electronic and information technologies enable people to collect required information or to trade directly over networks via computers, making computers a requisite tool in people's work, learning, entertainments, leisure activities, and daily life.
For people to access two or more computers at the same time, there is developed an automatic switch to enable a user to automatically switch among different signal paths. FIG. 1 shows a conventional automatic switch 40 that is configured into a box 41. The box 41 is internally provided with a circuit board (not shown). Ports 42, 43, and 44 for various types of signal cable connectors are provided on peripheral walls of the box 41. In most cases, the box 41 includes outer walls that are made of metal material or rigid plastic material and assembled together by means of screws (not shown). The automatic switch 40 is normally positioned on a host enclosure of a computer configuration and tends to unexpectedly fall off the host enclosure to result in a damaged circuit board due to vibration. Moreover, when a high humidity exists, moisture in the air tends to attach to the circuit board to cause short circuit. Repair or maintenance of the circuit board is therefore required.